The Food and Drug Administration has asked doctors, dentists, pharmacists and other healthcare professionals to stop giving patients high-dose acetaminophen, the active ingredient in the popular pain-reliever Tylenol. Pills, capsules, tablets, syrups and other formulations that contain more than 325 milligrams of acetaminophen have not been shown to reduce pain better than lower doses of the medication; however, such high levels of the drug can cause liver damage, the FDA explained in a recommendation issued Tuesday. Pharmacists who are asked to fill prescriptions for medications with more than 325 mg of acetaminophen should contact the doctor or dentist who ordered it and see if a lower dose would suffice, the recommendation said.